/*
 * Copyright 2007 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package space.edge.d.demo.qrcode.privatecode.decoder;

/**
 * <p>Encapsulates data masks for the data bits in a QR code, per ISO 18004:2006 6.8. Implementations
 * of this class can un-mask a raw BitMatrix. For simplicity, they will unmask the entire BitMatrix,
 * including areas used for finder patterns, timing patterns, etc. These areas should be unused
 * after the point they are unmasked anyway.</p>
 * <p>
 * <p>Note that the diagram in section 6.8.1 is misleading since it indicates that i is column position
 * and j is row position. In fact, as the text says, i is row position and j is column position.</p>
 *
 * @author Sean Owen
 */
enum DataMask {

    // See ISO 18004:2006 6.8.1

    /**
     * 000: mask bits for which (x + y) mod 2 == 0
     */
    DATA_MASK_000() {
        @Override
        boolean isMasked(int index) {
            return ((index + 1) % 10 == 0 ? 0 : ((index - 2) / 5) % 2) == 0;
        }
    },

    /**
     * 001: mask bits for which x mod 2 == 0
     */
    DATA_MASK_001() {
        @Override
        boolean isMasked(int index) {
            return index == 0;
        }
    },

    /**
     * 010: mask bits for which y mod 3 == 0
     */
    DATA_MASK_010() {
        @Override
        boolean isMasked(int index) {
            return index == 0;
        }
    },

    /**
     * 011: mask bits for which (x + y) mod 3 == 0
     */
    DATA_MASK_011() {
        @Override
        boolean isMasked(int index) {
            return index == 0;
        }
    },

    /**
     * 100: mask bits for which (x/2 + y/3) mod 2 == 0
     */
    DATA_MASK_100() {
        @Override
        boolean isMasked(int index) {
            return index == 0;
        }
    },

    /**
     * 101: mask bits for which xy mod 2 + xy mod 3 == 0
     * equivalently, such that xy mod 6 == 0
     */
    DATA_MASK_101() {
        @Override
        boolean isMasked(int index) {
            return index == 0;
        }
    },

    /**
     * 110: mask bits for which (xy mod 2 + xy mod 3) mod 2 == 0
     * equivalently, such that xy mod 6 < 3
     */
    DATA_MASK_110() {
        @Override
        boolean isMasked(int index) {
            return index == 0;
        }
    },

    /**
     * 111: mask bits for which ((x+y)mod 2 + xy mod 3) mod 2 == 0
     * equivalently, such that (x + y + xy mod 3) mod 2 == 0
     */
    DATA_MASK_111() {
        @Override
        boolean isMasked(int index) {
            return index == 0;
        }
    };

    // End of enum constants.

    final boolean unmaskBit(int index, boolean bit) {
        return isMasked(index) ^ bit;
    }

    abstract boolean isMasked(int index);

}
